In a particularly economical bearing manufacturing technique known generally as "Siamese stamping," bearing races are stamped from a single blank so as to efficiently use the costly bearing quality steel. A central circle, or central annulus, is cut from the blank to be used for the inner race, while the remaining outer annulus is used for the outer race. Essentially the whole blank is used, with very little scrap. The outermost portion of the inner race and the innermost portion of the outer race are stamped or otherwise formed so as to provide radially confronting pathways for a ball complement, and the circular edges of the pathways create a pair of axially spaced annular gaps. It is most economical to stamp the races from thin, flat stock, so the pathways generally conform closely to the ball complement, and there is not a great deal of extra metal to work with in the areas where the pathways are formed. Consequently, the annular gaps do not have the large axial depth that the annular gap between the races of a conventional radial bearing has. There is therefore not sufficient room in the shallow gaps to mount a conventional bearing seal, such as a snap shield. While there is room for a conventional O-ring type seal, using an O-ring does not leave much lubricant containing volume around the ball complement, due to the close conformation of the pathways to the ball complement. Still, the annular gaps must somehow be sealed if the bearing is to be used in a harsh environment, such as a steerable McPherson strut vehicle suspension, with its strong road spray.
Two examples of a bearing manufactured by the above technique may be seen in German Offenlegungsschrift DT 2431935 A1. In the FIG. 2 embodiment, the inner and outer races are single pieces, and the ball complement is conrad assembled between the pathways. Therefore, while it is necessary to somehow seal the annular gaps, it is not necessary to retain the races to each other, as the ball complement itself serves to do that. Often, however, a full ball complement is desirable, especially in limited space, high load applications, like a vehicle suspension. A conrad assembled bearing cannot provide a full ball complement. The FIG. 1 embodiment shown in the above patent does allow a full complement, by bifurcating the inner and outer races. Each inner and outer race is formed from two identical race members. Two blanks of flat stock are each stamped and split along a circle, each blank providing one inner and one outer race member. The ball complement is sandwiched between the two inner and the two outer race members, which are then axially secured together to complete the bearing. This makes it possible to insert a full ball complement. The bifurcated assembly, of course, has the same shallow annular gaps that must be sealed. An additional drawback of the bifurcated structure is that, until the race members are secured together around the ball complement, or bolted to some other structure, there is nothing to prevent them from axially separating at the annular gaps. It is not feasible, in the bifurcated structure, to retain the race members together by radially overlapping the metal of the race member pathways, as the pathways are generally too thin and there is not enough extra metal in that area, as noted above.
A bearing assembly that deals with the problems of sealing and unitization in a bearing assembly having bifurcated races is disclosed in U.S. Pat. No. 4,362,344, assigned to the assignee of the present invention. As disclosed there, the circular edges of the inner race pathway do not radially overlap those of the outer race pathway, but the edges of the inner race member pathways are extended axially to form an axial space. So forming the inner race members is more difficult than just splitting them along a circle, of course, but the axial space in the annular gap is used to advantage. The axial space allows an annular elastomer seal of suitable thickness to be snap fitted into the gaps, filling the axial spaces and sealing the assembly. While the edges of the inner and outer pathways do not overlap one another, they both radially overlap the seal. The inner race members are secured together with separate structure, so the net effect of the pathway-seal overlap is that the outer race members are prevented from axially separating from the inner race members, creating a unitized bearing assembly. However, the strength of that retention can only be as strong as the thickness of the elastomer seal material. Also, the seals are inevitably exposed, sticking radially outwardly from the annular gaps over the outside surfaces of the outer races. Therefore, extra care during shipping and handling, as well as after installation, is necessary to protect the seal. The bearing assembly also has the drawback noted above of a limited lubricant containing volume. This is especially a problem with a full ball complement, as there is almost no circumferential space between the balls to hold lubricant. Therefore, the assembly could not be used in as harsh an environment as it could if it held more lubricant.